JPH04223229A - Light power meter and light coupler manufacturing device using it - Google Patents

Abstract

PURPOSE:To obtain a light power meter which responds repidly and has a wide dynamic range. CONSTITUTION:An electrical signal corresponding to an incident light power is obtained by a light detecting element, is amplified in parallel by a plurality of amplifiers 31-34 with a different amplification factor, and then is converted to a digital signal by an A/D converter. The amplification rate needs not to be switched even when the incident light power is greatly varied by performing amplification in parallel with the amplifiers having a different amplification factor and it is not needed to wait until a circuit is becomes stable, thus resulting in an rapid response.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical power meter and an optical coupler manufacturing apparatus constructed using the optical power meter.

0002

2. Description of the Related Art A conventional optical power meter usually includes a photodetector element 1 such as a photodiode that generates a current signal corresponding to the power of incident light, a current-voltage conversion circuit 2, and an amplifier circuit, as shown in FIG. 3, signal processing circuit 4, and A
/D converter 5 measures the optical power, and the control circuit 6 controls the current-voltage conversion circuit 2 or the amplifier circuit 3 by controlling the amplification factor etc. to change the range. , the optical power in a wide range is measured and displayed on the display 7 and the data is output.

Here, the photodetecting element 1 is a photodiode or the like that generates a current output proportional to the power of incident light. The current-voltage conversion circuit 2 converts its output current into a voltage, and performs a conversion of E=kI, where I is an input current and E is an output current. Note that k is a conversion coefficient. Range switching is performed by changing this conversion coefficient k. The amplifier circuit 3 performs voltage amplification,
By changing the amplification factor, you can change the range. The signal processing circuit 4 performs various signal processing such as removing fluctuation factors such as noise. The A/D converter 5 converts the output voltage of the signal processing circuit 4 into a digital signal. The control circuit 6 is usually composed of a microcomputer, and reads the signal from the A/D converter 5 to determine whether the range is appropriate. If the range is not appropriate, it issues a range switching signal to switch the range, and if it is appropriate, the control circuit 6 is configured with a microcomputer. The corresponding optical power is calculated from the signal, and the data is output and displayed on the display 7.

The A/D converter 5 has a resolution corresponding to the number of bits, and the minimum voltage difference that can be determined is determined with respect to the full-scale voltage. Therefore,
It is thought that using a high-resolution A/D converter with a large number of bits would allow detailed measurements over a wide range from small voltages to large voltages, but in reality, such A/D converters
Not only are converters expensive, but it is difficult to widen and stabilize the dynamic range of the input system of the A/D converter, making them susceptible to noise and the like, making it difficult to obtain high precision.

[0005] Therefore, in the past, the amplification factor in the input system of the A/D converter 5 was switched as described above to achieve highly accurate measurement over a wide dynamic range of incident light power.

[0006]

[Problem to be Solved by the Invention] However, when switching the amplification factor in the input system of an A/D converter in this way, it takes time for the output voltage to stabilize after switching, so the incident light power fluctuates. When making such a switch, a problem arises in that it takes a very long time to obtain measurement data. This is particularly problematic when the optical power changes, since it is not possible to make measurements that follow the changes.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an optical power meter with a wide dynamic range, which is improved so that measurement time is reduced even when the power of incident light varies greatly.

Another object of the present invention is to provide an improved optical coupler manufacturing apparatus that allows optical couplers to be manufactured easily by using an optical power meter that has a short measurement time and a wide dynamic range. .

[0009]

[Means for Solving the Problems] An optical power meter according to the present invention includes: a photoelectric conversion means for generating an electric signal corresponding to the power of incident light; a plurality of amplification means each having a different amplification factor for amplifying the electric signal; Since the amplification means on the input side of the means for converting into digital signals does not change the amplification factor, it is necessary to wait until the amplification means becomes stable. Even if the power of the incident light disappears and the power of the incident light changes, it can be immediately followed and measured.

Furthermore, the optical coupler manufacturing apparatus according to the present invention includes a means for heating a plurality of optical fibers that are arranged in advance in parallel and whose side surfaces are in contact with each other, and a means for stretching the plurality of optical fibers in the length direction. a light input means for inputting light from one end face of one of the plurality of optical fibers, and light emitting from the other end face of each optical fiber of the plurality of optical fibers; The optical power meter is equipped with the above-mentioned optical power meter that measures the power of the optical power meter, and a means for controlling the above-mentioned stretching means according to the output of this optical power meter. Therefore, the optical power measurement value corresponding to the degree of stretching can be immediately fed back to the stretching means to determine the degree of stretching, making it possible to easily manufacture an optical coupler.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing an optical power meter according to an embodiment of the present invention. As shown in this diagram, a photodetecting element 1 such as a photodiode that generates a current signal corresponding to the power of incident light, and a A voltage conversion circuit 2, a plurality of (four in this example) amplifier circuits 31-34, a plurality (four in this example) of signal processing circuits 41-44, and a plurality (four in this example) of signal processing circuits. It is composed of A/D converters 51 to 54, a control circuit 6, and a display 7.

Here, incident light from an optical fiber is measured, and an InGaAs ternary PIN photodiode with an FC connector and a light receiving diameter of 300 μm is used as the photodetecting element 1. The current-voltage conversion circuit 2 and the amplifier circuits 31 to 34 are constructed using operational amplifier ICs,
The four amplifier circuits 31 to 34 have amplification factors of 1 and 1, respectively.
The magnifications are 0x, 100x, and 1000x. A commercially available personal computer is used as the control circuit 6, and A/D converters 51 to 54 are built-in personal computers with a resolution of 16 bits. As the display 7, a CRT display device was used.

In this way, four parallel systems are provided after the photodetector element 1 and the current-voltage conversion circuit 2, including the amplifier circuits 31 to 34, the signal processing circuits 41 to 44, and the A/D converters 51 to 54. Therefore, the range is 0 dBm to -10 dBm in a system including the amplifier circuit 31 with a 1x amplification factor, and -10 dBm to -20 dB in a system including an amplifier circuit 32 with a 10x amplification factor.
m, -20 in a system including an amplifier circuit 33 with an amplification factor of 100 times.
dBm to -30 dBm, and -30 dBm to -40 dBm can be respectively handled in parallel in a system including an amplifier circuit 34 with an amplification factor of 1000 times. Therefore, since there is no need to switch the amplification factor in the current-voltage conversion circuit 2 or the amplifier circuits 31 to 34, there is no need to wait for the amplification factor to stabilize after switching, and the optical power can Even if the optical power fluctuates, the control circuit 6 can immediately output the measurement data of the optical power, and it can also be displayed on the display 7.

FIG. 3 is a block diagram showing a second embodiment. In the embodiment shown in this figure, the A/D converter 5 has 1
The outputs of the four signal processing circuits 41 to 44 are switched by a switching circuit 8. As this switch 8, a multiplexer was used. The control circuit 6 reads the output of the A/D converter 5, and selects the output of the A/D converter 5 for one input that the control circuit 6 determines to be appropriate. That is, by sequentially switching the switching circuit 8, the outputs of the four signal processing circuits 41 to 44 are switched to A.
/D converter 5 to obtain respective digital signals. This makes it possible to select the largest digital value among the inputs of the A/D converter 5 that do not overflow. The control circuit 6 uses the system weighting corresponding to the selected digital value to perform calculations for converting the digital value into optical power.

In this case, the time for one conversion, that is, the switching time of the switching circuit 8 + the conversion time of the A/D converter 5 is 25
Since it can be about μsec, 0dBm to -4
Optical power in the 0dBm range, display resolution 0.01d
Bm enables measurements of 100 times/second. In other words, the switching time of the switching circuit 8 and the conversion time of the A/D converter 5 are orders of magnitude faster than the stabilization time after switching the amplification factors of the current-voltage conversion circuit 2 and the amplifier circuit 3, and the response time is much faster. You can switch without any problem.

FIG. 4 shows an optical coupler manufacturing apparatus using the optical power meter shown in FIG. 2 or 3. In this figure, two silica-based glass optical fibers 11 and 12 are placed in parallel in advance and are held by clampers 13 and 14 with their side surfaces in contact with each other. The gap is extended in the length direction. Between the clampers 13 and 14, the optical fibers 11 and 12 are heated from the side by a burner 16. That is, a fused and drawn optical fiber coupler is manufactured by fusing two optical fibers 11 and 12 at their sides. The position of the burner 16 is controlled by a burner position control device 17.

In such an optical coupler manufacturing apparatus, the light branching ratio depends on the amount of stretching. Therefore, it is necessary to input light from one end of one optical fiber 11 using the light source 18 and control the amount of stretching while monitoring the power of the light emitted from the other ends of the two optical fibers 11 and 12. Become. The light emitted from the other ends of the optical fibers 11 and 12 is measured by the optical power meters 21 and 22 shown in FIG. 2 or 3 described above. Then, the measured optical power data is sent to the controller 23 to control the stretching machine 15 and the burner position control device 17. As mentioned above, the optical power meters 21 and 22 have quick response and can follow and measure fluctuations in optical power, so they can optimize the position of the burner 16 and gradually extend it. The branching ratio, which changes moment by moment, can be immediately captured and reflected in the amount of stretching. In this manner, when the desired branching ratio is reached, the stretching machine 15 is stopped and the burner 16 is moved back, thereby making it possible to obtain an optical coupler having the desired branching ratio.

[0018]

As described above, according to the optical power meter of the present invention, it is possible to measure optical power with good response and a wide dynamic range. Therefore, even if the incident light power fluctuates widely over a wide range,
It is possible to immediately follow this and obtain measurement data without any time delay.

Further, according to the optical coupler manufacturing apparatus of the present invention, since an optical power meter having good responsiveness and a wide dynamic range is used, optical couplers with desired characteristics can be easily manufactured. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example.

FIG. 2 is a block diagram of a first embodiment of an optical power meter according to the present invention.

FIG. 3 is a block diagram of a second embodiment of an optical power meter according to the invention.

FIG. 4 is a block diagram of an embodiment of an optical coupler manufacturing apparatus according to the present invention.

[Explanation of symbols]

1 Photodetection element 2
Current voltage conversion circuit 3, 3
1-34 Amplifier circuit 4, 41-44 Signal processing circuit 5, 51-55 A/D converter 6
Control circuit 7
Display 8
Switching circuit 11, 12 Optical fiber 1
3, 14 Clamper

Claims (2)

[Claims] 1. A photoelectric conversion means for generating an electric signal corresponding to the power of incident light, a plurality of amplification means each having a different amplification factor for amplifying the electric signal, and means for converting the output of the amplification means into a digital signal. An optical power meter characterized by comprising: 2. Means for heating a plurality of optical fibers that are arranged in advance in parallel and whose side surfaces are in contact with each other; and means for stretching the plurality of optical fibers in the length direction;
A light input means for inputting light from one end face of one of the plurality of optical fibers, and measuring the power of light emitted from the other end face of each optical fiber of the plurality of optical fibers. An optical coupler manufacturing apparatus comprising: the optical power meter according to claim 1; and means for controlling the stretching means in accordance with the output of the optical power meter.